So far, the theory of equilibrium selection in the infinitely repeated
prisoner's dilemma is insensitive to communication possibilities. To address
this issue, we incorporate the assumption that communication reduces -- but
does not entirely eliminate -- an agent's uncertainty that the other agent
follows a cooperative strategy into the theory. Because of this, agents still
worry about the payoff from cooperating when the other one defects, i.e. the
sucker's payoff S, and, games with communication are more conducive to
cooperation than games without communication. This theory is supported by data
from laboratory experiments, and by machine learning based evaluation of the
communication content